The present invention relates to a sight apparatus for a shotgun. More particularly, the present invention relates to an adjustable sight which is designed to provide an indication of a pattern of shot from the shotgun.
Shotguns may shoot individual slugs or loads of multiple projectiles called shot. Unless hunting large game, the preferred load for a shotgun is shot. These shot are carried in a shell configured for the gauge of the bore of the shotgun. Shells are available in different loads having different sizes, configurations, and numbers of projectiles. This shot is expelled from the smooth bore of the barrel of the shotgun. Upon exiting the bore of the shotgun, all the shot in a load has a component of velocity along the axis of the bore of the barrel. Each individual projectile also has a component of velocity perpendicular to the axis of the barrel. The magnitude of the component of velocity perpendicular to the axis of the barrel of any projectile is generally randomly distributed between zero and an upper limit. Thus as shot exits the barrel of a shotgun, each individual projectile travels longitudinally along the extended axis of the barrel toward the target and most of the individual projectiles also travel radially away from the extended axis in a random direction. Thus at any plane perpendicular to the extended axis, the shot is generally randomly distributed in a circular pattern.
The upper limit of the magnitude of the component of perpendicular velocity of any individual projectile is determined by the internal configuration of the bore and length of the barrel of the shotgun. The radius of the circular pattern through which substantially all of the shot pass at a given distance from the end of the barrel is determined by the upper limit of the magnitude of the component of perpendicular velocity of any individual projectile. The choke of a shotgun barrel refers to how effectively the barrel limits the magnitude of the component of perpendicular velocity of shot exiting the barrel, and thus also provides an indication of the expected diameter of the shot pattern at any given distance. A full-choke barrel minimizes the magnitude of the component of vertical velocity so that at a given distance the radius of the shot pattern is relatively small. An open-choke barrel does not limit the magnitude of the component of perpendicular velocity of shot exiting the barrel as well as a full choke barrel so that at any given distance the radius of the circular pattern through which the shot from an open-choke barrel passes is larger than that the radius of the circular pattern through which the shot from a full-choke barrel passes. Modified-choke barrels provide a pattern having a radius between the full-choke barrel and the open-choke barrel at any given distance.
Immediately upon leaving the barrel, projectiles propelled from firearms, are subject to wind resistance inhibiting the motion of the projectile along the axis of the barrel and gravity providing a substantially constant force on the projectile toward the earth. Thus sighting directly along the axis of the bore of the barrel, i.e. bore-sighting, does not provide a proper indication of where a projectile leaving the barrel will hit at a given distance. Sights for firearms generally provide a means for altering the height of a component of the sight so that the axis of the barrel is elevated relative to the sight line to compensate for gravitational forces and wind resistance. Sights are generally calibrated on a firing range so that the projectile leaving the barrel impacts the target within the sight at a given distance.
The sight apparatus of the present invention is calibrated for a particular shotgun. The sight is adjustable along a barrel of the gun to provide an indication of the pattern of shot at various distances. The sight is open and does not block the shooter""s view. In other words, the shooter still has a full range of vision. The sight may be calibrated to shoot high or low depending on the preference of the shooter and on the gun. The colored lens of the sight apparatus provides an indication of the pattern of shot on a target, regardless of the distance of the target from the gun.
In accordance with the present invention, a sight apparatus for a shotgun having a barrel extending along a longitudinal axis, a muzzle end, and a defined choke inducing shot expelled from the barrel to fall within a defined shot pattern at a defined target distance, includes a lens and a frame coupled to the barrel for longitudinal and lateral movement relative to the longitudinal axis of the barrel. The lens is mounted to the frame and the frame and lenses are adjustable so that a shooting eye of a shooter will see the lens superimposed over the defined shot pattern when the sight apparatus is calibrated for the defined target distance. According to another aspect of the invention, the lens is colored. An additional aspect of the invention is that the entire shot pattern is visible to the shooting eye through the lens. According to yet another aspect of the invention, the longitudinal and lateral adjustment of the lens may be accomplished with a longitudinally extending track pivotally mounted to the barrel to pivot about a pivot point adjacent the muzzle end. The track includes a plurality of lateral slots and the frame is configured to be received in any one of the lateral slots.
A sight apparatus for a shotgun having a barrel having a longitudinal axis, a muzzle end, and a defined choke inducing shot expelled from the barrel to fall within a defined shot pattern at a defined target distance, includes a lens mounted to the barrel for longitudinal and lateral movement relative to the longitudinal axis. Additionally, the entire shot pattern is visible to the shooting eye through the lens when the sight apparatus is properly calibrated. Also, the lens is colored. The longitudinal displacement between the muzzle end of the barrel and the lens in a properly calibrated sight apparatus increases as the choke of the barrel becomes more open. The lateral displacement between the axis of the barrel and the lens in a properly calibrated sight apparatus increases as the target distance increases.
Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of an illustrated embodiment exemplifying the best mode of carrying out the invention as presently perceived.